VSIGetMemFileBuffer(): delay destroying VSIMemFile on bUnlinkAndSeize (…

…fixes OSGeo#4158) (OSGeo#4179)
tmSreedarsh · Aug 8, 2021 · ac50212 · ac50212
1 parent 244a4dc
commit ac50212
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Showing 2 changed files with 22 additions and 2 deletions.
diff --git a/autotest/cpp/test_cpl.cpp b/autotest/cpp/test_cpl.cpp
@@ -3486,4 +3486,21 @@ namespace tut
 
         CPLQuadTreeDestroy(hTree);
     }
+    // Test bUnlinkAndSize on VSIGetMemFileBuffer
+    template<>
+    template<>
+    void object::test<50>()
+    {
+        VSILFILE *fp = VSIFOpenL("/vsimem/test_unlink_and_seize.tif", "wb");
+        VSIFWriteL("test", 5, 1, fp);
+        GByte *pRawData = VSIGetMemFileBuffer("/vsimem/test_unlink_and_seize.tif", nullptr, true);
+        ensure(EQUAL(reinterpret_cast<const char *>(pRawData), "test"));
+        ensure(VSIGetMemFileBuffer("/vsimem/test_unlink_and_seize.tif", nullptr, false) == nullptr);
+        ensure(VSIFOpenL("/vsimem/test_unlink_and_seize.tif", "r") == nullptr);
+        ensure(VSIFReadL(pRawData, 5, 1, fp) == 0);
+        ensure(VSIFWriteL(pRawData, 5, 1, fp) == 0);
+        ensure(VSIFSeekL(fp, 0, SEEK_END) == 0);
+        CPLFree(pRawData);
+        VSIFCloseL(fp);
+    }
 } // namespace tut
diff --git a/gdal/port/cpl_vsi_mem.cpp b/gdal/port/cpl_vsi_mem.cpp
@@ -1034,8 +1034,11 @@ GByte *VSIGetMemFileBuffer( const char *pszFilename,
         CPLDebug("VSIMEM", "VSIGetMemFileBuffer() %s: ref_count=%d (before)",
                  poFile->osFilename.c_str(), poFile->nRefCount);
 #endif
-        CPLAtomicDec(&(poFile->nRefCount));
-        delete poFile;
+        poFile->pabyData = nullptr;
+        poFile->nLength = 0;
+        poFile->nAllocLength = 0;
+        if (CPLAtomicDec(&(poFile->nRefCount)) == 0)
+            delete poFile;
     }
 
     return pabyData;